题目内容
(16分)如图所示,质量为m、半径为R的光滑半圆形轨道A静置于光滑水平面上,质量为
的物块B(可视为质点)从轨道右端从静止开始释放,求物块B滑至轨道最低处时:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532755720.png)
(1)A、B的速度大小vA、vB; (2)B对轨道压力大小.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532740450.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532755720.png)
(1)A、B的速度大小vA、vB; (2)B对轨道压力大小.
(1)
、
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532849642.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532802702.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532833774.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532849642.png)
试题分析:(1)物块B滑至轨道最低处过程中
物块与轨道系统机械能守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035328651123.png)
系统动量守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532880702.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532802702.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532833774.png)
(2)设B受轨道支持力为N,由牛顿第二定律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035329271179.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532943613.png)
由牛顿第三定律得:B对轨道压力大小
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532958690.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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